1. Field of the Invention
The present invention relates to a potentiometer and more particularly to a slide-type potentiometer, such as a carbon composition and a wire wound potentiometer of slide-type, including a vertically movable actuating rod, which is used for controlling the rotational speed of an electric motor with the actuating rod interlocked to a foot-pedal actuator mechanism. In the slide-type potentiometer, a sliding contact is slideably disposed to be electrically in contact with a resistor element such as a carbon composition and a wire wound resistor element and mechanically coupled with the actuating rod so that the resistance of the potentiometer may be varied by moving the actuating rod with a foot pedal vertically.
2. Description of the Prior Art
In hithereto known slide-type potentiometers for controlling the rotational speed of the electric motors, the foot-pedal actuator mechanism interlocked to those potentiometers requires a relatively large number of parts and thus its construction is relatively complicated, and therefore when such hitherto known slide-type potentiometers are used, the foot-pedal actuator mechanism becomes relatively high in cost since it requires considerably time in the assembling process, and besides since the slide-type potentiometers have the opened portions and apertures, those are very susceptible to deposition of dust and foreign particles which give rise to failure.